Surge protective devices

Abstract

A surge protector having a hot line, a load line, a neutral line, and a ground line, the surge protector is provided. The surge protector has a fuse coupled between the hot line and the load line to protect loads from current surges. A differential mode protection circuit is coupled between the load line and the neutral line to protect loads from differential mode transient voltage surges. A common mode protection circuit is coupled to the load line, the neutral line and the ground line to protect loads from common mode transient voltage surges. An indicator circuit monitors the differential mode protection circuit and the common mode protection circuit to provide an indication as to the operational status of the surge protector.

What is claimed is: 
     
       1. A surge protector having a hot line, a load line, a neutral line, and a ground line, the surge protector comprising:
 a fuse coupled between the hot line and the load line; 
 a differential mode protection circuit coupled between the load line and the neutral line; 
 a common mode protection circuit coupled to the load line, the neutral line and the ground line, wherein the common mode protection circuit includes a first transient suppressor coupled between the load line and an intermediate point, a second transient suppressor coupled between the neutral line and the intermediate point, and a third transient suppressor coupled between the ground line and the intermediate point; and 
 an indicator circuit, the indicator circuit coupled at least between the hot line and the neutral line and capable of indicating an operational status of the surge protector, the indicator circuit including a delay circuit coupled between the load line and the neutral line capable of delaying an output voltage raise of a full bridge rectifier circuit. 
 
     
     
       2. The surge protector of  claim 1 , wherein the indicator circuit comprises an indicator configured to activate when the surge protector is operational. 
     
     
       3. The surge protector of  claim 2 , wherein the indicator comprises a visible indicator. 
     
     
       4. The surge protector of  claim 3 , wherein the visible indicator comprises a light source. 
     
     
       5. The surge protector of  claim 2 , wherein the indicator comprises an audible indicator. 
     
     
       6. The surge protector of  claim 1 , wherein the indicator circuit comprises an indicator configured to activate when the surge protector is not operational. 
     
     
       7. The surge protector of  claim 6 , wherein the indicator comprises a visible indicator. 
     
     
       8. The surge protector of  claim 7 , wherein the visible indicator comprises a light source. 
     
     
       9. The surge protector of  claim 6 , wherein the indicator comprises an audible indicator. 
     
     
       10. The surge protector of  claim 1 , wherein the fuse is a surge rated fuse. 
     
     
       11. The surge protector of  claim 1 , wherein the differential mode protection circuit comprises at least one surge suppressor coupled between the load line and the neutral line. 
     
     
       12. The surge protector of  claim 11 , wherein the at least one surge suppressor comprises a varistor. 
     
     
       13. The surge protector of  claim 12 , wherein the varistor comprises a metal oxide varistor. 
     
     
       14. The surge protector of  claim 1 , wherein at least one of the first transient suppressor and the second transient suppressor comprises a varistor. 
     
     
       15. The surge protector of  claim 14 , wherein the varistor comprises a metal oxide varistor. 
     
     
       16. The surge protector of  claim 1 , wherein the at least one of the first transient suppressor and the second transient suppressor comprises a gas discharge suppressor. 
     
     
       17. The surge protector of  claim 16 , wherein the gas discharge suppressor comprises a gas discharge tube. 
     
     
       18. A surge protector having a hot line, a load line, a neutral line, and a ground line, the surge protector comprising:
 a fuse coupled between the hot line and the load line; 
 a differential mode protection circuit coupled between the load line and the neutral line, the differential mode protection circuit having at least one surge suppressor coupled between the load line and the neutral line; 
 a common mode protection circuit coupled to the load line, the neutral line and the ground line; wherein the common mode protection circuit includes:
 a first surge suppressor coupled between the ground line and an intermediate node; 
 a second surge suppressor coupled between the load line and the intermediate node; and 
 a third surge suppressor coupled between the neutral line and the intermediate node; and 
 
 
       an indicator circuit, the indicator circuit coupled at least between the hot line and the neutral line and capable of indicating an operational status of the surge protector, the indicator circuit including a delay circuit coupled between the load line and the neutral line capable of delaying an output voltage rise of a full bridge rectifier circuit. 
     
     
       19. The surge protector of  claim 18 , wherein the indicator circuit comprises a substantially DC power source and an indicator configured to activate when the surge protector is operational. 
     
     
       20. The surge protector of  claim 18 , wherein the indicator circuit comprises a substantially DC power source and an indicator configured to activate when the surge protector is not operational. 
     
     
       21. The surge protector of  claim 18 , wherein the first surge suppressor coupled between the ground line and the intermediate node comprises a gas discharge suppressor. 
     
     
       22. The surge protector of  claim 18 , wherein the second surge suppressor coupled between the hot line and the intermediate node comprises a varistor. 
     
     
       23. The surge protector of  claim 18 , wherein the third surge suppressor coupled between the neutral line and the intermediate node comprises a varistor. 
     
     
       24. A surge protection device, comprising
 a housing; 
 a hot line, a load line, a neutral line, and a ground line; 
 a fuse coupled between the hot line and the load line; 
 a differential mode protection circuit coupled between the load line and the neutral line; 
 a common mode protection circuit coupled to the load line, the neutral line and the ground line, wherein the common mode protection circuit includes a first transient suppressor coupled between the load line and an intermediate point, a second transient suppressor coupled between the neutral line and the intermediate point, and a third transient suppressor coupled between the ground line and the intermediate point; and 
 an indicator circuit, the indicator circuit coupled at least between the hot line and the neutral line and capable of indicating an operational status of the surge protector, the indicator circuit including a delay circuit coupled between the load line and the neutral line capable of delaying an output voltage rise of a full bridge rectifier circuit. 
 
     
     
       25. The surge protection device of  claim 24 , wherein the indicator circuit comprises an indicator configured to activate when the surge protection device is operational. 
     
     
       26. The surge protection device of  claim 24 , wherein the indicator circuit comprises an indicator configured to activate when the surge protection device is not operational. 
     
     
       27. The surge protection device of  claim 24 , wherein the differential mode protection circuit comprises at least one surge suppressor coupled between the load line and the neutral line. 
     
     
       28. The surge protection device of  claim 27 , wherein the at least one surge suppressor comprises a varistor. 
     
     
       29. The surge protection device of  claim 24 , wherein at least one of the first transient suppressor and the second transient suppressor comprises a varistor.